Vertical cavity surface emitting laser (VCSEL) arrays pumped solid-state lasers

• US 7,430,231 B2
• Filed: 04/28/2006
• Issued: 09/30/2008
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Pavilion Integration Corporation
• Original Assignee: Pavilion Integration Corporation
• Inventors: Luo, Ningyi, Zhu, Sheng-Bai
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): Park; Kinam
• Application Number:
  US11/414,492
• Publication Number:
  US 20060245460A1
• Time in Patent Office: 886 Days
• Field of Search: 372/41, 372/70, 372/75, 372/10, 372/21, 372/22, 372/29.01
• US Class Current: 372/75
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/08054 Passive cavity elements acting on the polarization, e.g. a polarizer for branching or walk-off compensation quarter-wave plates in a Q-switch laser H01S3/1124, H01S3/115
• CPC Class Codes: H01S 3/094084 with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/1083 using parametric generation
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1312 by controlling the optical pumping
• CPC Class Codes: H01S 3/161 holmium
• CPC Class Codes: H01S 3/1611 neodymium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/1653 YLiF4(YLF, LYF)
• CPC Class Codes: H01S 3/1673 YVO4 [YVO]

Abstract

Solid-state lasers pumped by incoherent or partially coherent, monochromatic light sources such as high power VCSEL arrays. Efficient and uniform injection of pumping energy into gain medium is achieved through spectral match of the pump source with the gain medium absorption and multi-bounce reflections of unabsorbed pump light in a diffusing pump chamber. One preferred embodiment of the diffusing pump chamber is a hollow cylinder coaxially surrounding the gain medium. One or more transparent windows, slit-shaped or otherwise, for transmission of pump light are evenly distributed around the perimeter of the chamber and are parallel to the axis. Another preferred embodiment of the diffusing pump chamber is a highly reflecting compound parabolic concentrator. A 2-D VCSEL array is employed as the pump source and the gain medium is located at the focusing point of the chamber. This invention demonstrates solid-state lasers that are compact, robust, low-cost, and able to produce high power output in CW or pulse modes for practical applications. An important application of the present invention is high-power solid-state lasers featuring wavelength conversion such as optical parametric oscillation and second-harmonic generation. Another important application of the present invention is injection seeding, especially for pulse mode with high repetition rates.

Claims

1. A laser device comprising:

an active laser gain medium;

an optical cavity having a set of passive optical elements;

a pump assembly for generation of incoherent or partially coherent, monochromatic excitation light and for efficient and uniform injection of the excitation light into said active laser gain medium; and

a housing assembly, containing the optical cavity, the active laser gain medium, and the pump assembly;

wherein;

said housing assembly physically protects the laser system and effectively dissipates the heat generated during laser operation;

said pump assembly further comprising;

an excitation element having a two-dimensional VCSEL array to produce incoherent or partially coherent, monochromatic excitation light and

a power supply, electrically connected to the excitation element at the array level, for energizing the excitation element to produce the excitation light; and

a tubular diffusing pump chamber, its cross-section is shaped with two or more overlapping parabolic section(s), wherein

the two-dimensional VCSEL array forms one side of the chamber,

the rest part of the pump chamber surface is a reflector to the excitation wavelength,

the pump chamber effectively surrounds the active laser gain medium and in axial alignment with the gain medium,

the central axis of the active laser gain medium is located at or near the focus of the chamber, whereby a population of the active species becomes substantially inverted in response to excitation by incoherent or partially coherent monochromatic pump light, and

the effects of the excitation light on the gain medium is enhanced through multiple bounces from the inner surface of the pump chamber.

2. The laser device according to claim 1 further comprising:

a pulse controller for producing pulses of excitation light from the excitation element such that pulses of laser light are produced from the lasing element.

3. The laser device according to claim 1 further comprising:

a seed laser, which injects signal into the active gain medium for spectral and temporal mode control, and a mechanism for optical coupling, which extracts laser output generated from the active gain medium and isolates the seed laser from fed-back light.

4. The laser device according to claim 1 further comprising:

at least one nonlinear optical crystal, which is situated in the laser path for intracavity wavelength conversion.

5. The laser device according to claim 1 further comprising a Q-switch element for producing high-power laser pulses.